TIRE REPAIR

You do not repair it properly at the roadside. A correct repair requires removing the tire from the wheel so the technician can inspect the inner liner for damage that occurred while the tire was losing pressure, then installing a combination patch-and-plug from inside. Roadside plug kits and sealants are temporary measures to get you to a shop, not permanent repairs.

It can usually be repaired if the puncture is in the tread area, within the accepted size limit, not in or near the shoulder, and the tire was not driven flat. It cannot be repaired if the damage is in the sidewall, if the tire was run flat, if there is a bulge, or if tread depth is already at the wear limit.

The sidewall flexes with every rotation, thousands of times per hundred kilometres. Any repair material bonded to a surface under that much repeated flexing eventually separates, and when it does the failure is sudden and complete. There is no repair method the industry considers safe for sidewall damage.

Running a tire flat, even briefly, generates enormous heat and lets the rim flange cut into the deflated casing. The inner liner creases and the internal structure is compromised in ways not visible from outside. A tire driven flat should be replaced, not repaired, even if it looks fine once reinflated.

The same principles apply: tread area only, away from the shoulder, within size limits, and inspected internally. Light truck tires often carry higher loads and inflation pressures, which raises the stakes on a marginal repair. If a truck tire is used for towing or hauling near its load rating, err toward replacement rather than a borderline repair.

There is no fixed number, but repairs must not overlap and multiple repairs raise the risk profile. If a tire has already been repaired more than once, or a new puncture sits close to an existing repair, replacement is the safer call. A professional assessing it internally can advise on the specific case.